In this remarkably well-researched and provocative book, authors Enrico Tuccinardi and Salvatore Mazzariello use a letter intercepted by Italian authorities in May, 1901, to uncover a clandestine transnational world populated by revolutionary plots, a deposed queen, and police spies and government officials dedicated to foiling these unlikely allies’ efforts. It is an outstanding model of historical research and methodology that deserves attention from scholars outside of the fields of Italian and radical history. However, it ultimately fails to substantiate its most sensational argument.

The document around which the study is organized was penned in May of 1901 by famed Italian anarchist Errico Malatesta, then residing in exile in London, and addressed to a heretofore unknown companion in Paris. The letter uses veiled language and nicknames—including, importantly, references to “la Signora”—to discuss the anarchists’ ongoing international efforts to spark a revolution in Italy. Although this source has long been known to Italian historians, Tuccinardi and Mazzariello are the first researchers to solve many of the mysteries surrounding it, including its intended recipient (convincingly shown to be the anarchist Felice Vezzani).

The authors utilize a wealth of primary sources, including a number of previously overlooked documents in French and Spanish, and they include transcriptions of many of these—either in excerpted form or in their entirety—within the book’s seven chapters and appendix. This meticulous research brings to light a loose-knit, transnational radical network that included not only anarchists, but sympathetic socialists and less easily definable individuals like Angelo Insogna, a onetime anarchist turned Bourbon restorationist and confidant of the deposed Queen of the Two Sicilies, Maria Sofia. The authors also reveal the international web of informants, police spies, and political operatives dedicated to surveilling and disrupting these subversive threats.

At the center of the book’s argument is a peculiar episode, long known to specialists in the field but little understood. For several days in February of 1901, Errico Malatesta visited Maria Sofia’s residence in Neuilly, France, in the company of two fellow anarchists (revealed by Tuccinardi and Mazzariello to have been Charles Malato and Enrico Difendi). The meeting was facilitated by Angelo Insogna, and resulted in Maria Sofia—the “la Signora” mentioned in Malatesta’s letter written three months later—providing an unspecified amount of financial assistance to the anarchists. This unlikely meeting and “hybrid alliance” has fed speculation and controversy ever since it was first revealed publicly by Benedetto Croce in 1926, and the authors of Architettura di una chimera provide the most detailed accounting to date of what is known about this encounter. They make a very convincing case that, as Croce originally suggested, the former queen and the antimonarchist anarchists had joined forces in a conspiracy to break Gaetano Bresci, the anarchist assassin of King Umberto I. Malatesta, according to this argument, hoped that the liberation of the regicide would destabilize the legitimacy of the Italian state in the minds of the population, while Maria Sofia ached for revenge against the House of Savoy which, under Umberto’s father Emmanuel II, had deposed her from her throne during Italy’s wars of unification. The authors further support the theory, albeit without conclusive corroborating evidence, that knowledge of this plot led Prime Minister Giovanni Giolitti to secretly order the murder of Bresci, whose death in Santo Stefano prison on May 22, 1901, was ruled a suicide but has remained shrouded in suspicion ever since. Although none of these claims are new, here they are made more forcefully and convincingly than ever before.

The same cannot be said for the argument made in the book’s final and most controversial chapter: that both Malatesta and Maria were likely involved in Bresci’s assassination of Umberto I in July of the previous year. This conspiracy theory, first put forth by Giolitti himself, has long been proposed in popular writings and refuted by historians of Italian anarchism. Unfortunately, the careful documentation and argumentation characteristic of the book’s previous chapters do not carry through to the end. Despite the authors’ claim to be offering “a historiographical revision of primary importance” (p. 5), they offer no new or compelling evidence in support of their speculation that Maria Sofia supplied “logistical and financial support” to Bresci (p. 150), or that Malatesta had knowledge of and a role in Bresci’s act. Instead, they deduce that the “converging interests” of these two parties make such cooperation likely (p. 154), and rely on Roberto Gremmo’s book Gli anarchici che uccisero Umberto I°: Gaetano Bresci, il “Biondino” e i tessitori biellesi di Paterson (2000) for evidence of a wider conspiracy that may have included Malatesta. However, although the authors praise Gremmo for building his argument “on a base of meticulous research” (p. 143), they neglect to mention that his book does not contain a single citation, or that its conclusions have been challenged by numerous other scholars.

Despite the weakness of its final chapter, Architettura di una chimera is an engrossing portrait of a hidden turn-of-the-century world of revolutionaries, spies, and conspiracies, based on impressive archival sleuthing. Although it positions itself somewhat narrowly within the historiography of Italian anarchism and Maria Sofia’s intrigues, most of its historiographical arguments are confined to copious and often extensive footnotes, leaving the book’s narrative unencumbered and compelling. And though it may not revolutionize our understanding of anarchism or Umberto I’s assassination, it is nevertheless an extraordinary piece of historical detective work.